AUSTIN (AP) – More than four-fifths of school districts offer no sex education or only teach abstinence in Texas, which has one of the country’s highest teen birth rates, according to a study released Tuesday.

The study commissioned by Texas Freedom Network, a left-leaning education watchdog group, found that 25 percent of roughly 1,000 school districts statewide didn’t offer any sex education during the 2015-2016 school year and about 58 percent only taught students to abstain from sex.

The remaining 17 percent, including eight of the 10 largest school districts in America’s second most-populous state, stress abstinence, which they are required to do under a 1995 Texas law. But they also teach students about other sexual topics, including birth control.

The 17-percent figure is actually a marked increase from a 2009 study, which found that 96 percent of Texas school districts taught abstinence only.

The number of districts that offer no sex education rose even more dramatically, from 2 percent in the study eight years ago to a quarter of them today. A major factor in districts dropping their sex education curriculums was a 2009 decision by the Republican-controlled Texas Legislature to scrap passing a health course as a high school graduation requirement.

Of the districts that still teach sex education, 31 percent of the ones in urban areas offer instruction on more than just abstinence, while only about 5 percent of rural districts do.

The U.S. Department of Health and Human Services in 2014 ranked Texas tied with New Mexico for fourth nationwide in birth rates for mothers ages 15 to 19. Some studies have found that comprehensive sex education that includes birth control information is more effective than abstinence-only programs at reducing teen pregnancy rates.

But 25 other states in addition to Texas require stressing abstinence, according to the Guttmacher Institute, a pro-abortion rights research organization. Eighteen states and the District of Columbia require students to be taught about contraception.

The authors of the new study sent surveys as open records requests to Texas’ 10 largest school districts and to a sample of 148 other districts seen as representative of the rest of the state. A breakdown by student population wasn’t provided, though the eight largest districts that teach more than just abstinence educate a combined 17 percent of the state’s roughly 5.3 million public students.

The study found that many districts not offering abstinence only lessons rely on two major sex education programs designed specifically for Texas that incorporate classroom games, discussions and role-playing to help students feel more empowered.

Republican Gov. Greg Abbott has been less vocal preaching abstinence than his predecessor, Rick Perry, who boasted that he knew from his personal life that it worked. Still, the Texas House approved a state budget prohibiting schools from distributing sex education materials produced by abortion providers like Planned Parenthood, which in the past helped devise such materials for some districts, including Austin’s.

Meanwhile, Texas’ state-approved health textbooks stress abstinence and haven’t been updated since 2004. Some abstinence-only classroom materials characterize using contraception as “high risk” sexual behavior, while at least one school cautioned students that sexual activity can lead to suicide.

State Rep. Mary Gonzalez, a Democrat from Clint, proposed legislation that would guarantee sex education programs provide accurate medical information. It has little chance of passing in the Legislature, but Gonzalez said she’ll appeal to her anti-abortion colleagues, arguing that better sex education could lead to fewer terminated pregnancies.

“If you’re truly for limiting abortions, then here’s one way to do it,” Gonzalez said.

The study also found that 25 percent of Texas school districts taught no sex education.